1 files changed, 834 insertions, 269 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 80a27284dbf..d6f1996de62 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -40,6 +40,12 @@ struct map_lookup {
 	struct btrfs_bio_stripe stripes[];
 };
 
+static int init_first_rw_device(struct btrfs_trans_handle *trans,
+				struct btrfs_root *root,
+				struct btrfs_device *device);
+static int btrfs_relocate_sys_chunks(struct btrfs_root *root);
+
+
 #define map_lookup_size(n) (sizeof(struct map_lookup) + \
 			    (sizeof(struct btrfs_bio_stripe) * (n)))
 
@@ -69,25 +75,31 @@ static void unlock_chunks(struct btrfs_root *root)
 int btrfs_cleanup_fs_uuids(void)
 {
 	struct btrfs_fs_devices *fs_devices;
-	struct list_head *uuid_cur;
-	struct list_head *devices_cur;
 	struct btrfs_device *dev;
 
-	list_for_each(uuid_cur, &fs_uuids) {
-		fs_devices = list_entry(uuid_cur, struct btrfs_fs_devices,
-					list);
+	while (!list_empty(&fs_uuids)) {
+		fs_devices = list_entry(fs_uuids.next,
+					struct btrfs_fs_devices, list);
+		list_del(&fs_devices->list);
 		while(!list_empty(&fs_devices->devices)) {
-			devices_cur = fs_devices->devices.next;
-			dev = list_entry(devices_cur, struct btrfs_device,
-					 dev_list);
+			dev = list_entry(fs_devices->devices.next,
+					 struct btrfs_device, dev_list);
 			if (dev->bdev) {
 				close_bdev_excl(dev->bdev);
 				fs_devices->open_devices--;
 			}
+			fs_devices->num_devices--;
+			if (dev->writeable)
+				fs_devices->rw_devices--;
 			list_del(&dev->dev_list);
+			list_del(&dev->dev_alloc_list);
 			kfree(dev->name);
 			kfree(dev);
 		}
+		WARN_ON(fs_devices->num_devices);
+		WARN_ON(fs_devices->open_devices);
+		WARN_ON(fs_devices->rw_devices);
+		kfree(fs_devices);
 	}
 	return 0;
 }
@@ -257,6 +269,9 @@ static noinline int device_list_add(const char *path,
 				       disk_super->dev_item.uuid);
 	}
 	if (!device) {
+		if (fs_devices->opened)
+			return -EBUSY;
+
 		device = kzalloc(sizeof(*device), GFP_NOFS);
 		if (!device) {
 			/* we can safely leave the fs_devices entry around */
@@ -273,8 +288,9 @@ static noinline int device_list_add(const char *path,
 			kfree(device);
 			return -ENOMEM;
 		}
+		INIT_LIST_HEAD(&device->dev_alloc_list);
 		list_add(&device->dev_list, &fs_devices->devices);
-		list_add(&device->dev_alloc_list, &fs_devices->alloc_list);
+		device->fs_devices = fs_devices;
 		fs_devices->num_devices++;
 	}
 
@@ -288,58 +304,94 @@ static noinline int device_list_add(const char *path,
 
 int btrfs_close_extra_devices(struct btrfs_fs_devices *fs_devices)
 {
-	struct list_head *head = &fs_devices->devices;
+	struct list_head *tmp;
 	struct list_head *cur;
 	struct btrfs_device *device;
+	int seed_devices = 0;
 
 	mutex_lock(&uuid_mutex);
 again:
-	list_for_each(cur, head) {
+	list_for_each_safe(cur, tmp, &fs_devices->devices) {
 		device = list_entry(cur, struct btrfs_device, dev_list);
-		if (!device->in_fs_metadata) {
-			struct block_device *bdev;
-			list_del(&device->dev_list);
-			list_del(&device->dev_alloc_list);
+		if (device->in_fs_metadata)
+			continue;
+
+		if (device->bdev) {
+			close_bdev_excl(device->bdev);
+			device->bdev = NULL;
+			fs_devices->open_devices--;
+		}
+		if (device->writeable) {
+			list_del_init(&device->dev_alloc_list);
+			device->writeable = 0;
+			fs_devices->rw_devices--;
+		}
+		if (!seed_devices) {
+			list_del_init(&device->dev_list);
 			fs_devices->num_devices--;
-			if (device->bdev) {
-				bdev = device->bdev;
-				fs_devices->open_devices--;
-				mutex_unlock(&uuid_mutex);
-				close_bdev_excl(bdev);
-				mutex_lock(&uuid_mutex);
-			}
 			kfree(device->name);
 			kfree(device);
-			goto again;
 		}
 	}
+
+	if (fs_devices->seed) {
+		fs_devices = fs_devices->seed;
+		seed_devices = 1;
+		goto again;
+	}
+
 	mutex_unlock(&uuid_mutex);
 	return 0;
 }
 
-int btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
+static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
 {
-	struct list_head *head = &fs_devices->devices;
+	struct btrfs_fs_devices *seed_devices;
 	struct list_head *cur;
 	struct btrfs_device *device;
+again:
+	if (--fs_devices->opened > 0)
+		return 0;
 
-	mutex_lock(&uuid_mutex);
-	list_for_each(cur, head) {
+	list_for_each(cur, &fs_devices->devices) {
 		device = list_entry(cur, struct btrfs_device, dev_list);
 		if (device->bdev) {
 			close_bdev_excl(device->bdev);
 			fs_devices->open_devices--;
 		}
+		if (device->writeable) {
+			list_del_init(&device->dev_alloc_list);
+			fs_devices->rw_devices--;
+		}
+
 		device->bdev = NULL;
+		device->writeable = 0;
 		device->in_fs_metadata = 0;
 	}
-	fs_devices->mounted = 0;
-	mutex_unlock(&uuid_mutex);
+	fs_devices->opened = 0;
+	fs_devices->seeding = 0;
+	fs_devices->sprouted = 0;
+
+	seed_devices = fs_devices->seed;
+	fs_devices->seed = NULL;
+	if (seed_devices) {
+		fs_devices = seed_devices;
+		goto again;
+	}
 	return 0;
 }
 
-int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
-		       int flags, void *holder)
+int btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
+{
+	int ret;
+
+	mutex_lock(&uuid_mutex);
+	ret = __btrfs_close_devices(fs_devices);
+	mutex_unlock(&uuid_mutex);
+	return ret;
+}
+
+int __btrfs_open_devices(struct btrfs_fs_devices *fs_devices, void *holder)
 {
 	struct block_device *bdev;
 	struct list_head *head = &fs_devices->devices;
@@ -350,24 +402,18 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
 	struct btrfs_super_block *disk_super;
 	u64 latest_devid = 0;
 	u64 latest_transid = 0;
-	u64 transid;
 	u64 devid;
+	int seeding = 1;
 	int ret = 0;
 
-	mutex_lock(&uuid_mutex);
-	if (fs_devices->mounted)
-		goto out;
-
 	list_for_each(cur, head) {
 		device = list_entry(cur, struct btrfs_device, dev_list);
 		if (device->bdev)
 			continue;
-
 		if (!device->name)
 			continue;
 
-		bdev = open_bdev_excl(device->name, flags, holder);
-
+		bdev = open_bdev_excl(device->name, MS_RDONLY, holder);
 		if (IS_ERR(bdev)) {
 			printk("open %s failed\n", device->name);
 			goto error;
@@ -387,16 +433,32 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
 		if (devid != device->devid)
 			goto error_brelse;
 
-		transid = btrfs_super_generation(disk_super);
-		if (!latest_transid || transid > latest_transid) {
+		if (memcmp(device->uuid, disk_super->dev_item.uuid,
+			   BTRFS_UUID_SIZE))
+			goto error_brelse;
+
+		device->generation = btrfs_super_generation(disk_super);
+		if (!latest_transid || device->generation > latest_transid) {
 			latest_devid = devid;
-			latest_transid = transid;
+			latest_transid = device->generation;
 			latest_bdev = bdev;
 		}
 
+		if (btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_SEEDING) {
+			device->writeable = 0;
+		} else {
+			device->writeable = !bdev_read_only(bdev);
+			seeding = 0;
+		}
+
 		device->bdev = bdev;
 		device->in_fs_metadata = 0;
 		fs_devices->open_devices++;
+		if (device->writeable) {
+			fs_devices->rw_devices++;
+			list_add(&device->dev_alloc_list,
+				 &fs_devices->alloc_list);
+		}
 		continue;
 
 error_brelse:
@@ -410,11 +472,32 @@ error:
 		ret = -EIO;
 		goto out;
 	}
-	fs_devices->mounted = 1;
+	fs_devices->seeding = seeding;
+	fs_devices->opened = 1;
 	fs_devices->latest_bdev = latest_bdev;
 	fs_devices->latest_devid = latest_devid;
 	fs_devices->latest_trans = latest_transid;
+	fs_devices->total_rw_bytes = 0;
 out:
+	return ret;
+}
+
+int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
+		       int flags, void *holder)
+{
+	int ret;
+
+	mutex_lock(&uuid_mutex);
+	if (fs_devices->opened) {
+		if (fs_devices->sprouted) {
+			ret = -EBUSY;
+		} else {
+			fs_devices->opened++;
+			ret = 0;
+		}
+	} else {
+		ret = __btrfs_open_devices(fs_devices, holder);
+	}
 	mutex_unlock(&uuid_mutex);
 	return ret;
 }
@@ -481,12 +564,12 @@ error:
  */
 static noinline int find_free_dev_extent(struct btrfs_trans_handle *trans,
 					 struct btrfs_device *device,
-					 struct btrfs_path *path,
 					 u64 num_bytes, u64 *start)
 {
 	struct btrfs_key key;
 	struct btrfs_root *root = device->dev_root;
 	struct btrfs_dev_extent *dev_extent = NULL;
+	struct btrfs_path *path;
 	u64 hole_size = 0;
 	u64 last_byte = 0;
 	u64 search_start = 0;
@@ -496,8 +579,11 @@ static noinline int find_free_dev_extent(struct btrfs_trans_handle *trans,
 	int start_found;
 	struct extent_buffer *l;
 
-	start_found = 0;
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
 	path->reada = 2;
+	start_found = 0;
 
 	/* FIXME use last free of some kind */
 
@@ -581,7 +667,6 @@ check_pending:
 	/* we have to make sure we didn't find an extent that has already
 	 * been allocated by the map tree or the original allocation
 	 */
-	btrfs_release_path(root, path);
 	BUG_ON(*start < search_start);
 
 	if (*start + num_bytes > search_end) {
@@ -589,10 +674,10 @@ check_pending:
 		goto error;
 	}
 	/* check for pending inserts here */
-	return 0;
+	ret = 0;
 
 error:
-	btrfs_release_path(root, path);
+	btrfs_free_path(path);
 	return ret;
 }
 
@@ -644,11 +729,10 @@ int btrfs_free_dev_extent(struct btrfs_trans_handle *trans,
 	return ret;
 }
 
-int noinline btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
+int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
 			   struct btrfs_device *device,
 			   u64 chunk_tree, u64 chunk_objectid,
-			   u64 chunk_offset,
-			   u64 num_bytes, u64 *start)
+			   u64 chunk_offset, u64 start, u64 num_bytes)
 {
 	int ret;
 	struct btrfs_path *path;
@@ -662,13 +746,8 @@ int noinline btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
 	if (!path)
 		return -ENOMEM;
 
-	ret = find_free_dev_extent(trans, device, path, num_bytes, start);
-	if (ret) {
-		goto err;
-	}
-
 	key.objectid = device->devid;
-	key.offset = *start;
+	key.offset = start;
 	key.type = BTRFS_DEV_EXTENT_KEY;
 	ret = btrfs_insert_empty_item(trans, root, path, &key,
 				      sizeof(*extent));
@@ -687,7 +766,6 @@ int noinline btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
 
 	btrfs_set_dev_extent_length(leaf, extent, num_bytes);
 	btrfs_mark_buffer_dirty(leaf);
-err:
 	btrfs_free_path(path);
 	return ret;
 }
@@ -735,12 +813,18 @@ error:
 	return ret;
 }
 
-static noinline int find_next_devid(struct btrfs_root *root,
-				    struct btrfs_path *path, u64 *objectid)
+static noinline int find_next_devid(struct btrfs_root *root, u64 *objectid)
 {
 	int ret;
 	struct btrfs_key key;
 	struct btrfs_key found_key;
+	struct btrfs_path *path;
+
+	root = root->fs_info->chunk_root;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
 
 	key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
 	key.type = BTRFS_DEV_ITEM_KEY;
@@ -763,7 +847,7 @@ static noinline int find_next_devid(struct btrfs_root *root,
 	}
 	ret = 0;
 error:
-	btrfs_release_path(root, path);
+	btrfs_free_path(path);
 	return ret;
 }
 
@@ -781,7 +865,6 @@ int btrfs_add_device(struct btrfs_trans_handle *trans,
 	struct extent_buffer *leaf;
 	struct btrfs_key key;
 	unsigned long ptr;
-	u64 free_devid = 0;
 
 	root = root->fs_info->chunk_root;
 
@@ -789,13 +872,9 @@ int btrfs_add_device(struct btrfs_trans_handle *trans,
 	if (!path)
 		return -ENOMEM;
 
-	ret = find_next_devid(root, path, &free_devid);
-	if (ret)
-		goto out;
-
 	key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
 	key.type = BTRFS_DEV_ITEM_KEY;
-	key.offset = free_devid;
+	key.offset = device->devid;
 
 	ret = btrfs_insert_empty_item(trans, root, path, &key,
 				      sizeof(*dev_item));
@@ -805,8 +884,8 @@ int btrfs_add_device(struct btrfs_trans_handle *trans,
 	leaf = path->nodes[0];
 	dev_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_item);
 
-	device->devid = free_devid;
 	btrfs_set_device_id(leaf, dev_item, device->devid);
+	btrfs_set_device_generation(leaf, dev_item, 0);
 	btrfs_set_device_type(leaf, dev_item, device->type);
 	btrfs_set_device_io_align(leaf, dev_item, device->io_align);
 	btrfs_set_device_io_width(leaf, dev_item, device->io_width);
@@ -819,9 +898,11 @@ int btrfs_add_device(struct btrfs_trans_handle *trans,
 
 	ptr = (unsigned long)btrfs_device_uuid(dev_item);
 	write_extent_buffer(leaf, device->uuid, ptr, BTRFS_UUID_SIZE);
+	ptr = (unsigned long)btrfs_device_fsid(dev_item);
+	write_extent_buffer(leaf, root->fs_info->fsid, ptr, BTRFS_UUID_SIZE);
 	btrfs_mark_buffer_dirty(leaf);
-	ret = 0;
 
+	ret = 0;
 out:
 	btrfs_free_path(path);
 	return ret;
@@ -832,11 +913,7 @@ static int btrfs_rm_dev_item(struct btrfs_root *root,
 {
 	int ret;
 	struct btrfs_path *path;
-	struct block_device *bdev = device->bdev;
-	struct btrfs_device *next_dev;
 	struct btrfs_key key;
-	u64 total_bytes;
-	struct btrfs_fs_devices *fs_devices;
 	struct btrfs_trans_handle *trans;
 
 	root = root->fs_info->chunk_root;
@@ -863,25 +940,6 @@ static int btrfs_rm_dev_item(struct btrfs_root *root,
 	ret = btrfs_del_item(trans, root, path);
 	if (ret)
 		goto out;
-
-	/*
-	 * at this point, the device is zero sized.  We want to
-	 * remove it from the devices list and zero out the old super
-	 */
-	list_del_init(&device->dev_list);
-	list_del_init(&device->dev_alloc_list);
-	fs_devices = root->fs_info->fs_devices;
-
-	next_dev = list_entry(fs_devices->devices.next, struct btrfs_device,
-			      dev_list);
-	if (bdev == root->fs_info->sb->s_bdev)
-		root->fs_info->sb->s_bdev = next_dev->bdev;
-	if (bdev == fs_devices->latest_bdev)
-		fs_devices->latest_bdev = next_dev->bdev;
-
-	total_bytes = btrfs_super_num_devices(&root->fs_info->super_copy);
-	btrfs_set_super_num_devices(&root->fs_info->super_copy,
-				    total_bytes - 1);
 out:
 	btrfs_free_path(path);
 	unlock_chunks(root);
@@ -892,11 +950,14 @@ out:
 int btrfs_rm_device(struct btrfs_root *root, char *device_path)
 {
 	struct btrfs_device *device;
+	struct btrfs_device *next_device;
 	struct block_device *bdev;
 	struct buffer_head *bh = NULL;
 	struct btrfs_super_block *disk_super;
 	u64 all_avail;
 	u64 devid;
+	u64 num_devices;
+	u8 *dev_uuid;
 	int ret = 0;
 
 	mutex_lock(&uuid_mutex);
@@ -907,14 +968,14 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
 		root->fs_info->avail_metadata_alloc_bits;
 
 	if ((all_avail & BTRFS_BLOCK_GROUP_RAID10) &&
-	    btrfs_super_num_devices(&root->fs_info->super_copy) <= 4) {
+	    root->fs_info->fs_devices->rw_devices <= 4) {
 		printk("btrfs: unable to go below four devices on raid10\n");
 		ret = -EINVAL;
 		goto out;
 	}
 
 	if ((all_avail & BTRFS_BLOCK_GROUP_RAID1) &&
-	    btrfs_super_num_devices(&root->fs_info->super_copy) <= 2) {
+	    root->fs_info->fs_devices->rw_devices <= 2) {
 		printk("btrfs: unable to go below two devices on raid1\n");
 		ret = -EINVAL;
 		goto out;
@@ -941,15 +1002,15 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
 			printk("btrfs: no missing devices found to remove\n");
 			goto out;
 		}
-
 	} else {
-		bdev = open_bdev_excl(device_path, 0,
+		bdev = open_bdev_excl(device_path, MS_RDONLY,
 				      root->fs_info->bdev_holder);
 		if (IS_ERR(bdev)) {
 			ret = PTR_ERR(bdev);
 			goto out;
 		}
 
+		set_blocksize(bdev, 4096);
 		bh = __bread(bdev, BTRFS_SUPER_INFO_OFFSET / 4096, 4096);
 		if (!bh) {
 			ret = -EIO;
@@ -957,45 +1018,97 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
 		}
 		disk_super = (struct btrfs_super_block *)bh->b_data;
 		if (strncmp((char *)(&disk_super->magic), BTRFS_MAGIC,
-		    sizeof(disk_super->magic))) {
-			ret = -ENOENT;
-			goto error_brelse;
-		}
-		if (memcmp(disk_super->fsid, root->fs_info->fsid,
-			   BTRFS_FSID_SIZE)) {
+			    sizeof(disk_super->magic))) {
 			ret = -ENOENT;
 			goto error_brelse;
 		}
 		devid = le64_to_cpu(disk_super->dev_item.devid);
-		device = btrfs_find_device(root, devid, NULL);
+		dev_uuid = disk_super->dev_item.uuid;
+		device = btrfs_find_device(root, devid, dev_uuid,
+					   disk_super->fsid);
 		if (!device) {
 			ret = -ENOENT;
 			goto error_brelse;
 		}
+	}
 
+	if (device->writeable && root->fs_info->fs_devices->rw_devices == 1) {
+		printk("btrfs: unable to remove the only writeable device\n");
+		ret = -EINVAL;
+		goto error_brelse;
+	}
+
+	if (device->writeable) {
+		list_del_init(&device->dev_alloc_list);
+		root->fs_info->fs_devices->rw_devices--;
 	}
-	root->fs_info->fs_devices->num_devices--;
-	root->fs_info->fs_devices->open_devices--;
 
 	ret = btrfs_shrink_device(device, 0);
 	if (ret)
 		goto error_brelse;
 
-
 	ret = btrfs_rm_dev_item(root->fs_info->chunk_root, device);
 	if (ret)
 		goto error_brelse;
 
-	if (bh) {
+	device->in_fs_metadata = 0;
+	if (device->fs_devices == root->fs_info->fs_devices) {
+		list_del_init(&device->dev_list);
+		root->fs_info->fs_devices->num_devices--;
+		if (device->bdev)
+			device->fs_devices->open_devices--;
+	}
+
+	next_device = list_entry(root->fs_info->fs_devices->devices.next,
+				 struct btrfs_device, dev_list);
+	if (device->bdev == root->fs_info->sb->s_bdev)
+		root->fs_info->sb->s_bdev = next_device->bdev;
+	if (device->bdev == root->fs_info->fs_devices->latest_bdev)
+		root->fs_info->fs_devices->latest_bdev = next_device->bdev;
+
+	num_devices = btrfs_super_num_devices(&root->fs_info->super_copy) - 1;
+	btrfs_set_super_num_devices(&root->fs_info->super_copy, num_devices);
+
+	if (device->fs_devices != root->fs_info->fs_devices) {
+		BUG_ON(device->writeable);
+		brelse(bh);
+		if (bdev)
+			close_bdev_excl(bdev);
+
+		if (device->bdev) {
+			close_bdev_excl(device->bdev);
+			device->bdev = NULL;
+			device->fs_devices->open_devices--;
+		}
+		if (device->fs_devices->open_devices == 0) {
+			struct btrfs_fs_devices *fs_devices;
+			fs_devices = root->fs_info->fs_devices;
+			while (fs_devices) {
+				if (fs_devices->seed == device->fs_devices)
+					break;
+				fs_devices = fs_devices->seed;
+			}
+			fs_devices->seed = device->fs_devices->seed;
+			device->fs_devices->seed = NULL;
+			__btrfs_close_devices(device->fs_devices);
+		}
+		ret = 0;
+		goto out;
+	}
+
+	/*
+	 * at this point, the device is zero sized.  We want to
+	 * remove it from the devices list and zero out the old super
+	 */
+	if (device->writeable) {
 		/* make sure this device isn't detected as part of
 		 * the FS anymore
 		 */
 		memset(&disk_super->magic, 0, sizeof(disk_super->magic));
 		set_buffer_dirty(bh);
 		sync_dirty_buffer(bh);
-
-		brelse(bh);
 	}
+	brelse(bh);
 
 	if (device->bdev) {
 		/* one close for the device struct or super_block */
@@ -1021,6 +1134,129 @@ out:
 	return ret;
 }
 
+/*
+ * does all the dirty work required for changing file system's UUID.
+ */
+static int btrfs_prepare_sprout(struct btrfs_trans_handle *trans,
+				struct btrfs_root *root)
+{
+	struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
+	struct btrfs_fs_devices *old_devices;
+	struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
+	struct btrfs_device *device;
+	u64 super_flags;
+
+	BUG_ON(!mutex_is_locked(&uuid_mutex));
+	if (!fs_devices->seeding || fs_devices->opened != 1)
+		return -EINVAL;
+
+	old_devices = kzalloc(sizeof(*fs_devices), GFP_NOFS);
+	if (!old_devices)
+		return -ENOMEM;
+
+	memcpy(old_devices, fs_devices, sizeof(*old_devices));
+	old_devices->opened = 1;
+	old_devices->sprouted = 1;
+	INIT_LIST_HEAD(&old_devices->devices);
+	INIT_LIST_HEAD(&old_devices->alloc_list);
+	list_splice_init(&fs_devices->devices, &old_devices->devices);
+	list_splice_init(&fs_devices->alloc_list, &old_devices->alloc_list);
+	list_for_each_entry(device, &old_devices->devices, dev_list) {
+		device->fs_devices = old_devices;
+	}
+	list_add(&old_devices->list, &fs_uuids);
+
+	fs_devices->seeding = 0;
+	fs_devices->num_devices = 0;
+	fs_devices->open_devices = 0;
+	fs_devices->seed = old_devices;
+
+	generate_random_uuid(fs_devices->fsid);
+	memcpy(root->fs_info->fsid, fs_devices->fsid, BTRFS_FSID_SIZE);
+	memcpy(disk_super->fsid, fs_devices->fsid, BTRFS_FSID_SIZE);
+	super_flags = btrfs_super_flags(disk_super) &
+		      ~BTRFS_SUPER_FLAG_SEEDING;
+	btrfs_set_super_flags(disk_super, super_flags);
+
+	return 0;
+}
+
+/*
+ * strore the expected generation for seed devices in device items.
+ */
+static int btrfs_finish_sprout(struct btrfs_trans_handle *trans,
+			       struct btrfs_root *root)
+{
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+	struct btrfs_dev_item *dev_item;
+	struct btrfs_device *device;
+	struct btrfs_key key;
+	u8 fs_uuid[BTRFS_UUID_SIZE];
+	u8 dev_uuid[BTRFS_UUID_SIZE];
+	u64 devid;
+	int ret;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	root = root->fs_info->chunk_root;
+	key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
+	key.offset = 0;
+	key.type = BTRFS_DEV_ITEM_KEY;
+
+	while (1) {
+		ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
+		if (ret < 0)
+			goto error;
+
+		leaf = path->nodes[0];
+next_slot:
+		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+			ret = btrfs_next_leaf(root, path);
+			if (ret > 0)
+				break;
+			if (ret < 0)
+				goto error;
+			leaf = path->nodes[0];
+			btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+			btrfs_release_path(root, path);
+			continue;
+		}
+
+		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+		if (key.objectid != BTRFS_DEV_ITEMS_OBJECTID ||
+		    key.type != BTRFS_DEV_ITEM_KEY)
+			break;
+
+		dev_item = btrfs_item_ptr(leaf, path->slots[0],
+					  struct btrfs_dev_item);
+		devid = btrfs_device_id(leaf, dev_item);
+		read_extent_buffer(leaf, dev_uuid,
+				   (unsigned long)btrfs_device_uuid(dev_item),
+				   BTRFS_UUID_SIZE);
+		read_extent_buffer(leaf, fs_uuid,
+				   (unsigned long)btrfs_device_fsid(dev_item),
+				   BTRFS_UUID_SIZE);
+		device = btrfs_find_device(root, devid, dev_uuid, fs_uuid);
+		BUG_ON(!device);
+
+		if (device->fs_devices->seeding) {
+			btrfs_set_device_generation(leaf, dev_item,
+						    device->generation);
+			btrfs_mark_buffer_dirty(leaf);
+		}
+
+		path->slots[0]++;
+		goto next_slot;
+	}
+	ret = 0;
+error:
+	btrfs_free_path(path);
+	return ret;
+}
+
 int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 {
 	struct btrfs_trans_handle *trans;
@@ -1028,26 +1264,34 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 	struct block_device *bdev;
 	struct list_head *cur;
 	struct list_head *devices;
+	struct super_block *sb = root->fs_info->sb;
 	u64 total_bytes;
+	int seeding_dev = 0;
 	int ret = 0;
 
+	if ((sb->s_flags & MS_RDONLY) && !root->fs_info->fs_devices->seeding)
+		return -EINVAL;
 
 	bdev = open_bdev_excl(device_path, 0, root->fs_info->bdev_holder);
 	if (!bdev) {
 		return -EIO;
 	}
 
+	if (root->fs_info->fs_devices->seeding) {
+		seeding_dev = 1;
+		down_write(&sb->s_umount);
+		mutex_lock(&uuid_mutex);
+	}
+
 	filemap_write_and_wait(bdev->bd_inode->i_mapping);
 	mutex_lock(&root->fs_info->volume_mutex);
 
-	trans = btrfs_start_transaction(root, 1);
-	lock_chunks(root);
 	devices = &root->fs_info->fs_devices->devices;
 	list_for_each(cur, devices) {
 		device = list_entry(cur, struct btrfs_device, dev_list);
 		if (device->bdev == bdev) {
 			ret = -EEXIST;
-			goto out;
+			goto error;
 		}
 	}
 
@@ -1055,18 +1299,31 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 	if (!device) {
 		/* we can safely leave the fs_devices entry around */
 		ret = -ENOMEM;
-		goto out_close_bdev;
+		goto error;
 	}
 
-	device->barriers = 1;
-	device->work.func = pending_bios_fn;
-	generate_random_uuid(device->uuid);
-	spin_lock_init(&device->io_lock);
 	device->name = kstrdup(device_path, GFP_NOFS);
 	if (!device->name) {
 		kfree(device);
-		goto out_close_bdev;
+		ret = -ENOMEM;
+		goto error;
 	}
+
+	ret = find_next_devid(root, &device->devid);
+	if (ret) {
+		kfree(device);
+		goto error;
+	}
+
+	trans = btrfs_start_transaction(root, 1);
+	lock_chunks(root);
+
+	device->barriers = 1;
+	device->writeable = 1;
+	device->work.func = pending_bios_fn;
+	generate_random_uuid(device->uuid);
+	spin_lock_init(&device->io_lock);
+	device->generation = trans->transid;
 	device->io_width = root->sectorsize;
 	device->io_align = root->sectorsize;
 	device->sector_size = root->sectorsize;
@@ -1074,12 +1331,22 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 	device->dev_root = root->fs_info->dev_root;
 	device->bdev = bdev;
 	device->in_fs_metadata = 1;
+	set_blocksize(device->bdev, 4096);
 
-	ret = btrfs_add_device(trans, root, device);
-	if (ret)
-		goto out_close_bdev;
+	if (seeding_dev) {
+		sb->s_flags &= ~MS_RDONLY;
+		ret = btrfs_prepare_sprout(trans, root);
+		BUG_ON(ret);
+	}
 
-	set_blocksize(device->bdev, 4096);
+	device->fs_devices = root->fs_info->fs_devices;
+	list_add(&device->dev_list, &root->fs_info->fs_devices->devices);
+	list_add(&device->dev_alloc_list,
+		 &root->fs_info->fs_devices->alloc_list);
+	root->fs_info->fs_devices->num_devices++;
+	root->fs_info->fs_devices->open_devices++;
+	root->fs_info->fs_devices->rw_devices++;
+	root->fs_info->fs_devices->total_rw_bytes += device->total_bytes;
 
 	total_bytes = btrfs_super_total_bytes(&root->fs_info->super_copy);
 	btrfs_set_super_total_bytes(&root->fs_info->super_copy,
@@ -1089,20 +1356,34 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 	btrfs_set_super_num_devices(&root->fs_info->super_copy,
 				    total_bytes + 1);
 
-	list_add(&device->dev_list, &root->fs_info->fs_devices->devices);
-	list_add(&device->dev_alloc_list,
-		 &root->fs_info->fs_devices->alloc_list);
-	root->fs_info->fs_devices->num_devices++;
-	root->fs_info->fs_devices->open_devices++;
-out:
+	if (seeding_dev) {
+		ret = init_first_rw_device(trans, root, device);
+		BUG_ON(ret);
+		ret = btrfs_finish_sprout(trans, root);
+		BUG_ON(ret);
+	} else {
+		ret = btrfs_add_device(trans, root, device);
+	}
+
 	unlock_chunks(root);
-	btrfs_end_transaction(trans, root);
-	mutex_unlock(&root->fs_info->volume_mutex);
+	btrfs_commit_transaction(trans, root);
 
-	return ret;
+	if (seeding_dev) {
+		mutex_unlock(&uuid_mutex);
+		up_write(&sb->s_umount);
 
-out_close_bdev:
+		ret = btrfs_relocate_sys_chunks(root);
+		BUG_ON(ret);
+	}
+out:
+	mutex_unlock(&root->fs_info->volume_mutex);
+	return ret;
+error:
 	close_bdev_excl(bdev);
+	if (seeding_dev) {
+		mutex_unlock(&uuid_mutex);
+		up_write(&sb->s_umount);
+	}
 	goto out;
 }
 
@@ -1160,7 +1441,15 @@ static int __btrfs_grow_device(struct btrfs_trans_handle *trans,
 	u64 old_total = btrfs_super_total_bytes(super_copy);
 	u64 diff = new_size - device->total_bytes;
 
+	if (!device->writeable)
+		return -EACCES;
+	if (new_size <= device->total_bytes)
+		return -EINVAL;
+
 	btrfs_set_super_total_bytes(super_copy, old_total + diff);
+	device->fs_devices->total_rw_bytes += diff;
+
+	device->total_bytes = new_size;
 	return btrfs_update_device(trans, device);
 }
 
@@ -1248,7 +1537,6 @@ int btrfs_del_sys_chunk(struct btrfs_root *root, u64 chunk_objectid, u64
 	return ret;
 }
 
-
 int btrfs_relocate_chunk(struct btrfs_root *root,
 			 u64 chunk_tree, u64 chunk_objectid,
 			 u64 chunk_offset)
@@ -1328,6 +1616,64 @@ int btrfs_relocate_chunk(struct btrfs_root *root,
 	return 0;
 }
 
+static int btrfs_relocate_sys_chunks(struct btrfs_root *root)
+{
+	struct btrfs_root *chunk_root = root->fs_info->chunk_root;
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+	struct btrfs_chunk *chunk;
+	struct btrfs_key key;
+	struct btrfs_key found_key;
+	u64 chunk_tree = chunk_root->root_key.objectid;
+	u64 chunk_type;
+	int ret;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
+	key.offset = (u64)-1;
+	key.type = BTRFS_CHUNK_ITEM_KEY;
+
+	while (1) {
+		ret = btrfs_search_slot(NULL, chunk_root, &key, path, 0, 0);
+		if (ret < 0)
+			goto error;
+		BUG_ON(ret == 0);
+
+		ret = btrfs_previous_item(chunk_root, path, key.objectid,
+					  key.type);
+		if (ret < 0)
+			goto error;
+		if (ret > 0)
+			break;
+
+		leaf = path->nodes[0];
+		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+
+		chunk = btrfs_item_ptr(leaf, path->slots[0],
+				       struct btrfs_chunk);
+		chunk_type = btrfs_chunk_type(leaf, chunk);
+		btrfs_release_path(chunk_root, path);
+
+		if (chunk_type & BTRFS_BLOCK_GROUP_SYSTEM) {
+			ret = btrfs_relocate_chunk(chunk_root, chunk_tree,
+						   found_key.objectid,
+						   found_key.offset);
+			BUG_ON(ret);
+		}
+
+		if (found_key.offset == 0)
+			break;
+		key.offset = found_key.offset - 1;
+	}
+	ret = 0;
+error:
+	btrfs_free_path(path);
+	return ret;
+}
+
 static u64 div_factor(u64 num, int factor)
 {
 	if (factor == 10)
@@ -1337,7 +1683,6 @@ static u64 div_factor(u64 num, int factor)
 	return num;
 }
 
-
 int btrfs_balance(struct btrfs_root *dev_root)
 {
 	int ret;
@@ -1353,6 +1698,8 @@ int btrfs_balance(struct btrfs_root *dev_root)
 	struct btrfs_trans_handle *trans;
 	struct btrfs_key found_key;
 
+	if (dev_root->fs_info->sb->s_flags & MS_RDONLY)
+		return -EROFS;
 
 	mutex_lock(&dev_root->fs_info->volume_mutex);
 	dev_root = dev_root->fs_info->dev_root;
@@ -1363,7 +1710,8 @@ int btrfs_balance(struct btrfs_root *dev_root)
 		old_size = device->total_bytes;
 		size_to_free = div_factor(old_size, 1);
 		size_to_free = min(size_to_free, (u64)1 * 1024 * 1024);
-		if (device->total_bytes - device->bytes_used > size_to_free)
+		if (!device->writeable ||
+		    device->total_bytes - device->bytes_used > size_to_free)
 			continue;
 
 		ret = btrfs_shrink_device(device, old_size - size_to_free);
@@ -1453,6 +1801,8 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size)
 	u64 old_total = btrfs_super_total_bytes(super_copy);
 	u64 diff = device->total_bytes - new_size;
 
+	if (new_size >= device->total_bytes)
+		return -EINVAL;
 
 	path = btrfs_alloc_path();
 	if (!path)
@@ -1469,6 +1819,8 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size)
 	lock_chunks(root);
 
 	device->total_bytes = new_size;
+	if (device->writeable)
+		device->fs_devices->total_rw_bytes -= diff;
 	ret = btrfs_update_device(trans, device);
 	if (ret) {
 		unlock_chunks(root);
@@ -1561,32 +1913,27 @@ static u64 noinline chunk_bytes_by_type(u64 type, u64 calc_size,
 		return calc_size * num_stripes;
 }
 
-
-int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
-		      struct btrfs_root *extent_root, u64 *start,
-		      u64 *num_bytes, u64 type)
+static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
+			       struct btrfs_root *extent_root,
+			       struct map_lookup **map_ret,
+			       u64 *num_bytes, u64 *stripe_size,
+			       u64 start, u64 type)
 {
-	u64 dev_offset;
 	struct btrfs_fs_info *info = extent_root->fs_info;
-	struct btrfs_root *chunk_root = extent_root->fs_info->chunk_root;
-	struct btrfs_path *path;
-	struct btrfs_stripe *stripes;
 	struct btrfs_device *device = NULL;
-	struct btrfs_chunk *chunk;
-	struct list_head private_devs;
-	struct list_head *dev_list;
+	struct btrfs_fs_devices *fs_devices = info->fs_devices;
 	struct list_head *cur;
+	struct map_lookup *map = NULL;
 	struct extent_map_tree *em_tree;
-	struct map_lookup *map;
 	struct extent_map *em;
+	struct list_head private_devs;
 	int min_stripe_size = 1 * 1024 * 1024;
-	u64 physical;
 	u64 calc_size = 1024 * 1024 * 1024;
 	u64 max_chunk_size = calc_size;
 	u64 min_free;
 	u64 avail;
 	u64 max_avail = 0;
-	u64 percent_max;
+	u64 dev_offset;
 	int num_stripes = 1;
 	int min_stripes = 1;
 	int sub_stripes = 0;
@@ -1594,19 +1941,17 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 	int ret;
 	int index;
 	int stripe_len = 64 * 1024;
-	struct btrfs_key key;
 
 	if ((type & BTRFS_BLOCK_GROUP_RAID1) &&
 	    (type & BTRFS_BLOCK_GROUP_DUP)) {
 		WARN_ON(1);
 		type &= ~BTRFS_BLOCK_GROUP_DUP;
 	}
-	dev_list = &extent_root->fs_info->fs_devices->alloc_list;
-	if (list_empty(dev_list))
+	if (list_empty(&fs_devices->alloc_list))
 		return -ENOSPC;
 
 	if (type & (BTRFS_BLOCK_GROUP_RAID0)) {
-		num_stripes = extent_root->fs_info->fs_devices->open_devices;
+		num_stripes = fs_devices->rw_devices;
 		min_stripes = 2;
 	}
 	if (type & (BTRFS_BLOCK_GROUP_DUP)) {
@@ -1614,14 +1959,13 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 		min_stripes = 2;
 	}
 	if (type & (BTRFS_BLOCK_GROUP_RAID1)) {
-		num_stripes = min_t(u64, 2,
-			    extent_root->fs_info->fs_devices->open_devices);
+		num_stripes = min_t(u64, 2, fs_devices->rw_devices);
 		if (num_stripes < 2)
 			return -ENOSPC;
 		min_stripes = 2;
 	}
 	if (type & (BTRFS_BLOCK_GROUP_RAID10)) {
-		num_stripes = extent_root->fs_info->fs_devices->open_devices;
+		num_stripes = fs_devices->rw_devices;
 		if (num_stripes < 4)
 			return -ENOSPC;
 		num_stripes &= ~(u32)1;
@@ -1641,15 +1985,19 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 		min_stripe_size = 1 * 1024 * 1024;
 	}
 
-	path = btrfs_alloc_path();
-	if (!path)
-		return -ENOMEM;
-
-	/* we don't want a chunk larger than 10% of the FS */
-	percent_max = div_factor(btrfs_super_total_bytes(&info->super_copy), 1);
-	max_chunk_size = min(percent_max, max_chunk_size);
+	/* we don't want a chunk larger than 10% of writeable space */
+	max_chunk_size = min(div_factor(fs_devices->total_rw_bytes, 1)